1. Field of the Invention
This invention relates to vehicle ice and chain traction systems which may be both rapidly deployed and rapidly retracted. More particularly, it relates to electrically-powered apparatuses for deploying a mounted system so that the components thereof are moved from a stowed configuration to an operable configuration.
2. Description of Related Art
Rapidly-deployable chain traction systems, which may be characterized generally as systems which fling short chain or cable segments beneath a road tire, have been known for some 90 years. Such a system is disclosed in U.S. Pat. No. 1,045,609 and in German Pat. No. No. 266,487 to W. H. Putnam for an ANTISKIDDING DEVICE. Throughout the years, various modifications and improvements have been made by numerous inventors. The following list is a representative list of a dozen other U.S. patents issued in this field:                U.S. Pat. No. 1,150,148 for a TRACTION AND ANTISKIDDING DEVICE;        U.S. Pat. No. 1,223,070 for an ANTISKIDDING DEVICE FOR VEHICLES;        U.S. Pat. No. 1,374,252 for an ANTISKID DEVICE FOR AUTOMOBILES;        U.S. Pat. No. 1,381,001 for a NON-SKID DEVICE FOR MOTOR AND OTHER VEHICLES;        U.S. Pat. No. 1,975,325 for an ANTISKID CHAIN AND MEANS FOR APPLYING AND REMOVING SAME;        U.S. Pat. No. 2,241,923 for an AUTOMATIC EMERGENCY TRACTION DEVICE FOR AUTOMOBILES;        U.S. Pat. No. 2,264,466 for an ANTISKID DEVICE FOR VEHICLES;        U.S. Pat. No. 2,277,036 for an ANTISKID DEVICE;        U.S. Pat. No. 2,283,948 for an AUTOMOBILE TRACTION DEVICE;        U.S. Pat. No. 2,442,322 for an ANTISKID DEVICE;        U.S. Pat. No. 4,299,310 for an ANTISKID DEVICE FOR MOTOR VEHICLES;        U.S. Pat. No. 4,800,992 for an ANTI-SKID DEVICE; and        U.S. Pat. No. Des. 286,524 for ANTI SKID CHAIN UNIT FOR VEHICLE TIRES.        
Referring now to the prior-art system of FIG. 1, a modern rapidly-deployable chain traction system 100 is depicted in its deployed configuration in this rear elevational view drawing. The chain traction system 100 is removably affixed to a drive axle 101 which incorporates a differential unit 102. Inner and outer road wheels (103A and 103B, respectively) are mounted on the visible half of the drive axle 101. On each road wheel (103A and 103B) is mounted a rubber tire (104A and 104B, respectively). The chain system 100 includes a friction drive disc 105 to which a plurality of chain segments 106A, 106B and 106C are attached. Chain segment 106A is depicted as being below the road surface 114, which is normally covered with a layer of snow or ice when the chain system 100 is in the deployed configuration. The friction drive disc 105 is rotatably mounted on a spindle 107 which is affixed to a support member 108 which is pivotally mounted to a mounting bracket 109. The mounting bracket is, in turn, bolted to the U-bolt shackles 113 which secure the suspension leaf springs 112 to the drive axle 101. The chain system 100 also includes a pneumatic cylinder 110 that is bolted to the mounting bracket 109. The pneumatic cylinder 110 has a slidable piston 111 that is held in a normally retracted position within cylinder 110 by spring biasing when pressure within cylinder 108 equals ambient pressure. The outer end of piston 111 is connected to support member 108. In the deployed configuration, the outer rim of friction drive disc 105 is pressed against the sidewall of tire 104A by a biasing force applied to support member 108 by piston 111. The biasing force is provided by pneumatic pressure inside pneumatic cylinder 110 which overcomes the spring biasing and causes piston 111 to extend. As the tire 104A rotates, the friction drive disc 105 also rotates with the chain segments 106 extended more or less radially therefrom. Thus each chain segment 106 is flung, sequentially, beneath the tread portion of tire 104A. In order to retract the system and disengage the friction drive disc 105 from contact with the sidewall of tire 104A, pneumatic pressure to pneumatic cylinder 110 is cut off, causing piston 111 to retract within cylinder 110 and raising the support member 108, the rotatably attached friction drive disc 105 and the attached chain segments 106. In the retracted configuration, the chain segments 106 do not touch the road surface 114.
Referring now to the side view of the modern prior-art modern rapidly-deployable chain traction system 100 of FIG. 2, the pneumatic deployment components and the mounting system are shown in greater detail. The mounting system shown is designed for use on vehicles which have a beam or live axle (i.e., one which incorporates a differential) 101. On each side of the vehicle, the apparatus mounts to U-bolt shackles which commonly secure the axle to a set of leaf springs 112 or an air bag assembly (not shown). If no U-bolts are present on the axle, a new set of U-bolts may be installed thereon and used to secure the system. In either case, the new mounting system is designed to be mounted directly to the exposed, threaded ends of the U-bolt shackles coupled to two sets of leaf springs (see 112 of FIG. 1). Each leaf spring set is coupled to the beam axle or axle housing (in the case of a live axle) with a pair of U-bolt shackles 113, which are tied together beneath the axle or axle housing with a flat tie plate 114 that is secured with four standard nuts 115 (two on each U-bolt). The mounting system is designed to be mounted directly to the exposed, threaded ends of the U-bolt shackles 113.
Although various mechanical means, such as cables and gears, have been used in the past to deploy chain traction systems, the current genre of chain traction systems relies almost exclusively on pneumatic cylinders for deployment. The primary problem associated with chain traction systems deployed by pneumatic cylinders is that the system may be too bulky for certain applications, such as installation on light-duty pickup trucks. One major problem associated with prior art gear-driven deployment systems is that uneven road surfaces imposed a potentially destructive shock load on the gear train when the chain traction system was in a retracted state. The shock loads had a tendency to shear the teeth off of gears in the deployment gear train. The shock loads could also fracture the housing used to contain the gear train. Another major problem associated with gear-driven deployment systems is that of grit, water, and corrosion related to inadequate protection of the gear train. For a gear-driven deployment system to function reliably, it is essential that all gears and all bearings be completely sealed from the harsh environment beneath the vehicle. Without proper sealing, the life expectancy of such systems would likely be no more than one winter season. Gear driven deployment systems for a chain traction system, if not manually operated, require some type of motor for automatic operation. For most vehicles, the only type of motor that makes sense is an electric motor, as electric power is readily available from the vehicle's storage battery. Although the automotive industry has solved the problems related to operation of electric motors in a harsh environment (e.g. engine starter motors), in the case of an electric-powered chain traction system, there is still the problem of how to start and stop the electric motor at the appropriate times. If limit switches are to be used, they must be completely sealed in order to protect their delicate circuitry.
What is needed is an electric-powered, gear-driven deployment system for chain traction systems that: (1) is sufficiently compact for installation on a wide variety of vehicles; (2) is completely sealed from the environment; (3) is relatively simple to install and operate; (4) is not subject to damage from shock loads imposed by uneven road surfaces; and (5) solves the problems related to limiting the travel of the device during deployment and retraction.